Climate proxy optimization - quantifying factors controlling growth, geochemistry and micro/nanostructural design of bivalve mollusk shells

计划中的项目旨在更好地了解控制双壳软体动物壳的增量生长、晶体结构和化学性质的环境和生物因素。双壳类越来越多地被用作过去气候的代表。然而，双壳类如何实际记录其壳中的环境条件（生长速率、微量元素和同位素地球化学、微/纳米结构设计）的基本机制却知之甚少。大多数描述贝壳生长与环境关系的模型都是归纳性的，并没有得到实验的支持。计划中的项目将通过分析自然和实验室条件下的壳形成来解决这一不足。主要焦点是：（1）双壳类将碳酸钙附着到其壳上的时间，（2）生物钟和生理学在壳分泌中的作用，（3）影响壳纳米结构和生长速率的因素，以及（4）与环境水有关的壳的化学和稳定同位素组成。如果外部因素保持不变（恒定的温度、食物供应、食物质量、光照等），贝壳的生长速度和化学成分是否仍会变化？壳的生长、化学和晶体结构在多大程度上受生物钟、生理或理化控制的支配？计划中的研究结果将大大提高我们对如何解释保存在双壳类软体动物外壳中的气候代用指标的理解。这将有助于优化信息检索模型，并提供一种手段，量化（新的）环境代理从双壳类软体动物的外壳。

The planned project aims at a better understanding of the environmental and biological factors governing incremental growth, crystal structures and chemistry of bivalve mollusk shells. Bivalves are increasingly used as proxies of past climates. Yet, the underlying mechanisms of how bivalves actually record environmental conditions in their shells (growth rate, trace and minor element and isotope geochemistry, micro/nanostructural design) are poorly understood. Most models describing the relation between shell growth and environment were inductively inferred and not supported by experiments. The planned project will address this insufficiency by analyzing shell formation under natural and laboratory conditions. Main foci are (1) the timing at which bivalves accrete calcium carbonate to their shells, (2) the role of biological clocks and physiology in shell secretion, (3) factors that influence shell nanostructures and growth rate and (4) the chemical and stable isotopic composition of the shells in relation to that of the ambient water. Will growth rate and chemistry of the shells vary still if external factors remain constant (constant temperature, food supply, food quality, light etc.)? To what extent is shell growth, chemistry and crystal structures governed by biological clocks, physiology or physiochemical controls? Results of the planned study will significantly improve our understanding of how to interpret climate proxies preserved in shells of bivalve mollusks. It will help optimizing models on information retrieval and offer a means of quantifying (new) environmental proxies obtained from bivalve mollusk shells.